Stick 'free photo editor' into your favourite search engine for some examples like Paint.Net and the GIMP.

If you're running Windows, various magazine cover discs often have things like Serif's editor too.

I have gimp on one of my laptops but I do also use photoshop.  I have to say though, that I have only just learnt how to do blurring with Photoshop and found that the gimp 'help' facility was very good and explained what I needed to do.

I think that new Pshop function will be aimed more at refining slightly blurred images where shutter speeds were too low. There is only so much the application can do with existing image data. If you use the correct techniques in Pshop to distort the pixels on an area, there is no way that that it can be reverted to the original image. But I have seen a few faces with minimal blurring where that tool would be able to reverse it enough to define the features to an identifiable extent.

If anyone needs help in Pshop, let me know and I'll put up a little tutorial for everyone. I did retouching for a living back home.

I've just downloaded Picasa in order to do some photo editting, and I seem to be doing ok with it so far.

One simple suggestion is to do two or more different blurs / concealments rather than relying on just one.

Agree to that.
Most recognizable part of the face are eyes. If they are blurred/covered first and than the whole face it should be enough.